污灌农田土壤镉污染状况及分布特征研究

The Study of the Pollution Situation and Distribution Characteristics of Cadmium in Farmland Soil Irrigated by Wastewater

对沈阳郊区某河沿岸部分乡镇的污灌农田土壤中重金属全镉含量进行了分析，评价了土壤镉污染状况，并探讨了该河沿岸土壤中镉的沿程分布特征、横向分布特征和垂向分布特征。结果表明，农田土壤重金属镉含量范围为0．15～8．23mg／kg，均值为1．75mg／kg。用土壤环境质量标准二级标准值对土壤中的全镉含量进行评价，平均镉污染指数为5．95，为重度污染；用土壤背景值标准评价，平均镉污染指数为5．95，超过当地背景值水平8．39倍，污灌已造成该地区重金属镉污染，且污染程度十分严重。该河渠从上游到下游，沿岸土壤镉含量呈降低趋势；横向分布上，距离该河渠越远，镉含量有逐渐减少的趋势；垂向分布上，表层土壤镉含量最高。

We determined the concentrations of total Cd in farmland soil of some of villages and towns along a sewage river in Shenyang suburb, evaluated the pollution situation of Cd, and discussed the longitudinal, transversal, vertical distribution of Cd in soil. The results indicated that the concentration was 0.15 - 8.23mg/kg, the average data was 1.75mg/kg, the average Cd pollution indices were 5.95 based on the China National Standard for Soil Environment Quality Grade Ⅱ , the soil was heavy - polluted;and the average Cd pollution indices was 5.95 based on soil backgroud values, and was 8.39 times more than local Cd backgroud values, so wastewater irrigation has made the soil badly Cd polluted. The concentrations of Cd are decreasing along the river; In the transversal direction, the faster the distance from the river is, the fewer serious the pollution caused by Cd is; The concentrations of Cd in the planting soil are the hightest in the vertical direction.